Microphone



Jfine 8 1926.

T. w. CASE v MICROPHONE Filed July is 1923 2 Sheets-Sheet 1 June 8 1926. 1,588,168

T. w. c sE MICROPHONE.

Filed July 18, 1923 2 Sheets-Sheet 2 Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

I ,THEODORE WILLARD CASE, OF AUBURN, NEW YORK, ASSIGZNOR TO CASE RESEARCH LABORATORY INCORPORATED, 'OIF AUBURN, NEW YORK, A CORPORATION OF NEW YORK.

mrcnoenonn.

Application filed July 1a, 1923. Serial in. 652,281.

This invention relates to certain improvements in method andapparatus for translatin sound wave variations into correspon ing variations of an electric current,

8 which latter variations may be used or translated as desired. Or perhaps difi'erently stated, the invention relates to a method or apparatus for producing variations of an electric current 1n accordance with 'or corresponding to sound wave variations, and specifically I term the apparatus a gas-thermo microphone.

The main object of the invention is to produce a highly sensitive instrument that Wlll intensify the sound effect and accurately translate sound Waves into corresponding variations of electric current, which latter variations may be re-translated with or without amplification, and with practically perfeet quality.

A further and more specific ob ect: resides in the elimination of distortion and foreign noises which might result from sympathetic diaphragm vibrations or other causes, and which afl'ect the sound waves to be translated or their transmission.

Other objects andadvantages relate to the details .of the apparatus, all' as will more fully appear from the following description, taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic illustration of the invention with the gas chamber shown in section.

Figure 2 is a front elevation of the, gas chamber.

Figure 3 is a diagrammatic view of a pcculiar adaptation of my invention.

The invention as shown comprises a sub stantially flat disk 1- which may perhaps preferably be of circular form, and is provided with an opening 2 in this disclosure of substantially rectangular form and positioned at substantially the central portion of the disk. Vithin this opening 1s arranged a short wire 3- formed of a material that varies its electrical resistance in accordance with its ten'iperature, and the opposite ends of this wire 3 are connecte in circuit with the positive and negative sides respectively of a variable sou ot potential, such as the battery any suitable means of well known construction being provided for efl'ecting desired variations of the source of potential utilized for heating the wire .3"+

lVithin this circuit may be positioned the tration, plus or minus .00001", and is in the form of a coil or low pitch spiral, as indicated, and is arranged in the opening -2 in the disk -1, and for illustrative purposes, this openin 2 may be about onehalf an inch long undone-quarter inch wide, and the Wire in its spiral form may be approximately one-quarter inch long so as to fit within the opening without contact therewith. However, the Opening maybe of various shapes, as circular, and the wire instead of being in spiral form may be of varied forms, as straight. and more than one wire -3-- may be used if desired.

The disk 1 may, as shown, he formed with an annular flange -8 penetrated by an inlet pipe f) adapted to carry a gas such as air, or a combination of gases, under pressure from any suitable source of supply, as a blower 1()-, and the rate of flow of gas from the pipe -9-- is adjusted for the best sensitivity of the apparatus, and may be just below the point where passage of gas through the opening 2 around the Wire 3 causes any noise, as for instance, a hissing sound. The sheet 11 of fabric, such as thin silk, may be secured across the open end of the flange 8- in any suitablemanner, and may be either taut or loose, so that in effect the rear of the gas chamber is partially open. and partof the gas or air may escape therethrough. The remainder of the gas or air entering the gas chamber -12 from the pipe 9- escapes through the opening -2- aroundlthe wire ,3- and tends to cool the wire at all times. The wire may be formed of any suitable material that varies itsfresistanee to the passage of an electric current in accordancewith its temperature, and altho variohs substances may a used, I have found platinum suitable for the urposer I r '4 P acing the filament in arr-opening ofldesired size, such as the opening into n1 sifies the sound; efieetrresultant frglm thfijfiii sired to translate, as in this position the soundflvaves to be translated are coming in a direction substantially opposite to the directron of the movement of the gas escaping throu h the opening 2-, and acting-to substituted for the primary -18 of the" cool t e spiral wire 3-. This positioning of the instrument is not, however, essential, altho' my present experience leads me to believe that's. more advantageous result is obtained in that manner.

mission, or in sound or voice translation or reproduction of any purpose, in Figure 2 I have illustrated a peculiar combination embodiment of my invention relating to the translation of variations in sound waves into corresponding variations of light waves which may be translated into a photographic record on a film by means of suitable apparatus, including a wire or member that varies its resistance to the passage of an electric current in accordance with its tempera-- ture combined with. means for'heating the wire'and preferably means for causing a current of gas to travel around the wire.

In the construction shown in Figure 2, the secondary 6- of the transformer, instead of being directly connected to a translat-ing device such as the telephone receivers 7 is connected in circuit with the fi1ament 13-.and grid '14- of an electroionic discharge device 15-, provision being made for heating'the filament, such as a heating circuit including abattery -1S. The filament I3 is further connected to the plate l6 of'the device 15 through this construction of apparatus, the variations in sound waves are translated by the resistance or wire -3- into variations of the electric current which. are amplified by the electroionic discharge device-l5' and its circuits, and are impressed upon the lamp -24-, thereby effecting variations in the light rays emanating from said lamp in accordance with sound wave variations.

The lamp 24 is a preferred illustration of a lamp suitable for my purpose, and may consist of a bulb -25 containing a suitable gas, such as helium under pressure, and two or more electrodes of suitable form, as illustrated two in number, the electrode 20- being of substantially cylindrical form and the'electrode 21- being in the form of a wire or filament that terminates adjacent the lower end of the cylindrical electrode and is spaced therefrom.

It will be obvious that this lamp may be transformer, and may be connected in circuit with the filament 13 and plate 16-- and the transformer 2G-' entirely omitted,

but the construction shown is perhaps pref-- Altho my invention 1sadapted fonj many' general uses, as for instance in wireless trans arable for my purpose. I

This apparatus constitutes a means for translating sound wave variations/ into a photographic record'of li ht variations corresponding to said sound wave variations.

Altho I have shown and described a specific construction of apparatus and preferred details thereof, I donot desire to limit myself to any particular form, shape or size of the wire -3- or of the open1ng-2--,

as a considerable variation is possible, nor do I desire to limit myself to the use ofa fabric wall 11 such as that illustrated, altho its use may be preferable, the broad idea of i this invention residing in the. positioning of an element that varies its resistance in accordance with its temperature in an opening in another element through which a stream I of air or gas passes under an adjusted pressure suited to the conditions of operation of the instrument.

I claim: v I 1.111 an apparatus of the class described, a gas chamber, means for supplyinggas under pressure to said chamber, an outlet from said'chamber, and a member that varies its electrical conductivity in accord,

ance with its temperature arranged in said outlet.

2. In an. apparatus of the class described,

a. gas chamber, means for supplying gas inc under pressure to said chamber, an outlet from said chamber, a member that varies its i electrical conductivity in accordance withits temperature arranged in said outlet, and a I source of potential in circult with said memv ber.

3. In an apparatus of the class described,

a gas chamber, means for supplying gas under pressure to said chamber, an outlet from said chamber, a member that varies its electrical conductivity in accordance with its temperature arranged in said outlet and said chamber having a wall formedof a porous member.

4. ln an apparatus of the class described, a gas chamber, means for supplying gas undcr pressure to said chamber, an outlet from Said chamber, a member that varies its electrical conductivity in accordance withits temperature arranged in said outlet, a source of potential in circuit with said member, and said chamber having a Wall formed of aporous member. 7

5. In an apparatus of the class described, a gas chamber, means for supplying gas un der pressure to said chamber, an outlet from said chamber, a member that varies its electrical conductivity in accordance with its temperature arranged in said outlet, and said chamber having a wall formed of a porous fabric.

6. In an apparatus of the class described, a gas chamber, means for supplying gas under pressure to said chamber, an outlet from said. chamber, and a member that varies its electrical conductivity in accordance with its temperatiue exposed to the current of gas escaping through said outlet.

7. In an apparatus of the class descr1bed, a disk having an opening therethrough, means for causing the passage of a forced current of gas through said opening, and a wire that varies its electrical resistance in accordance with its temperature exposed to the current of air escaping through said opening.

8. In an apparatus of the classdescribed, a disk having an opening therethrough, means for causing the passage of a forced current of gas through said opening, a Wire that varies its electrical resistance in accordance with its temperature exposed to the current of gas escaping through said opening, and means for maintaining said wire in a heated condition.

9. In an apparatus of the class described, a disk having an opening therethrough, means for causing the passage of a forced current of gas through said opening, a spiral wire that varies its electricalriihisttince in accordance with its temperature exposed to the current of gas escaping through said opening and means for maintaining said spiral wire in a heated conditio 10. In an apparatus of the class described, a gas chamber, means for supplying gas an; der pressure to said chamber, an outlet from said chamber, a member that varies its close trical conductivity in accordance with its; temperature exposed to the curnent of gas escaping through said outlet, and a source of potential in circuit with said member;

11. In an apparatus of the class describedg a gas chamber, means for supplying gas and der pressure to said chamber, an outlet from said chamber, a member that varies its elec trical conductivity in accordance with its temperature exposed to the current of gas escaping through said outlet, and a source of potential in circuit with said member, said member having a wall formed of a porous member.

12. In an apparatus of the class described, I

agas chamber having an opening in its front wall and having its rear wall comprising a porous member, means for supply- THEODORE WILLARD case. 

